Learn the theory and odds. Print out an *odds page* and see how every card, or 'out', has about a 2% chance of coming up on the turn or river, or 4% on both. From this it is easy to calculate the value of 6 outs, you have about a (6x4=) 24% chance of winning the hand.

A long-term winning poker player has to consistently make bets where this percentage value of the hand exceeds the percentage cost of the pot odds required to play.

This is exactly how casinos make their money. They hold a consistent odds advantage over the players, which unfailingly yields a positive return over the long term. As little as a 2-5% bias in your favor will produce much profit if exploited over many games, and by playing these two sets of odds against each other you can achieve exactly that: make a steady income, because the odds are 'in your favor'.

You can further increase the percentage of odds in your favor by simply playing on well-aspected days and playing on cheaper, easier tables on badly aspected days, or abstaining altogether.